VirtualDub Filters

This page contains the latest versions of some filters I made for VirtualDub. Put them into the VirtualDub plugins folder and restart VirtualDub to make them available from VirtualDub.

Deshaker - video stabilizer

Deinterlace - PAL movie

Deinterlace - area based

Field shift

Deinterlace - smooth (go here for Xesdeeni's great AVISynth port of this deinterlacer)

General convolution 3D

 


Deinterlace - PAL movie

In PAL, two kinds of video exist:

  • 50fps video with half vertical resolution (i.e. interlaced video) and

  • 25fps video with full vertical resolution (i.e. progressive video)

Both of these are usually captured as 25fps full resolution video which means that for 50fps video, each frame will consist of two subframes, or "fields". When these fields are merged into the full frame, interlace lines appear where the fields differ (usually due to motion). For this kind of video you should NOT use this deinterlacer. You need to use a "real" deinterlacer such as the area based deinterlacer below. You can also split the frames into their subframes and double the frame rate in which case you won't need to do any deinterlacing at all. But I recommend that you use my field shift filter below if you do this.
If, on the other hand, you have captured video with real 25fps (such as most PAL movies), there should be no interlace lines, since the fields belong to the same frame. However, sometimes the capture card gets it wrong and merges fields that should belong to different frames. This can easily be corrected by delaying all frames by one field which is exactly what the PAL movie deinterlacer does. This reconstruction is completely non-destructive. You should, however, always make sure your codec compresses the fields individually if you have this problem. Because interlace lines don't compress very well. MJPEG codecs usually have this option.
This filter needs to be first in the filter chain and before any clipping.

Settings

  • Swap fields: Sometimes the fields of a frame are in wrong order. Check this to fix that.

Version history:
Version 1.1: Added script support.

Note: To avoid confusion I think I should tell you that since I made this filter Donald Graft has added PAL deinterlacing to his smart deinterlacer too. It's called "phase shift by one field" and does everything my PAL deinterlacer does and a little more, so you might as well use that one instead since it's included with VirtualDub. But I'll keep this filter here anyway.

Download PAL movie deinterlacer
(Source code is available here)

 


Deinterlace - area based

This filter deinterlaces the frames only where it's needed by simply looking for interlace lines in each frame individually. When it detects interlace lines, it removes them using either blending or interpolation depending on your settings.
This is a very general deinterlacer since it doesn't care about how the interlace lines appeared. It could be due to motion or due to compression artifacts from 2-field compressed MPEG video (e.g. from digital TV). It's also perfect for when only parts of the frame area (or only some of the frames) suffer from interlace lines, such as a PAL movie with subtitles that changes between the two fields in a frame.
Note: Personally I hardly use this filter anymore. The smooth deinterlacer below is so much better, but only if you can deal with doubled framerate.

Settings

  • Show deinterlaced areas only: Areas that aren't deinterlaced are greyed (with a slight transparency).

  • Blend: Simply blends the interlace lines.

  • Interpolate: Discards every other interlace line and replaces them with the average of the rows above and below.

  • Threshold: Controls how much to deinterlace. Lower values deinterlaces more.

  • Edge detect: It's difficult to distinguish between interlace lines and real edges (which should not be deinterlaced). This value controls this decision. Higher value leaves more edges intact.

  • Log to file: The frames that have an interlaced area exceeding the given number of percent can be logged to a file which will be placed in the current directory (probably the same directory as the output video when encoding). It's called DeinterlaceAreaBased.log and contains frame numbers and the interlaced area (in %) for each frame. Can be used to detect frames that IVTC couldn't deinterlace properly.

Version history:
Version 1.4: Minor fix. Version 1.3 couldn't read the same processing settings and avisynth scripts as version 1.2. This version is backwards compatible. Thanks to Eric Borremans for bug report and testing.
Version 1.3: Added logging (suggested by Johan Rior).
Version 1.2: Added script support.
Version 1.1: Improved interlace detection algorithm. It doesn't do as much erroneous deinterlacing in detailed areas.

Download the area based deinterlacer
(Source code is available here)

 


Field shift

If you use the VirtualDub routines for MJPEG decoding and split each frame into two subframes and double the frame rate, you may notice that the output jumps up and down slightly. To make this disappear, every other frame should be shifted half a line. The easiest way to do this is to double the lines and shift every other frame down one line, which is exactly what this little filter does. You will probably want to reduce the size after this operation.
NOTE: You'll probably want to use the new smooth deinterlacer below instead of this one, since it maintains the frame's full resolution in static video.

Settings

  • Shift even frames: Choose between shifting even or odd frames.

Download the field shifter
(Source code is available here)

 


Deinterlace - smooth

This filter does almost the same as the area based deinterlacer above, except that this one delivers video in twice the frame rate, which results in smoother video. No temporal information is lost with this filter. In non-interlaced areas, two fields are combined to give a full resolution frame. In interlaced areas, the current field is interpolated up to full frame size (or it can blend with the previous field, which isn't a recommended option).

Like for the field shift filter above, the input video to this filter must consist of individual fields at 50 or 60fps. If the source is in MJPEG format, VirtualDub can split the frames for you. Otherwise, use AVISynth to split them with the following script:

AVISource("clip.avi")
ComplementParity
SeparateFields

...and open this script from VirtualDub. Remove the 'ComplementParity' line if the fields arrive in wrong order.

 

Settings

  • Colorcode: Areas are colored differently to help you find suitable parameter values.

    • Red - Deinterlaced areas

    • Blue - Non-static areas that would be deinterlaced if interlace patterns were found

    • Green - Static areas that do contain interlace patterns but are still left untouched

    • Grey - Static areas without interlace patterns

  • Blend: Blends this and previous field in interlaced areas. (You should probably avoid using this as it just blurs the video.)

  • Interpolate: Interpolate the field to full frame size in interlaced areas.

  • Alternate field order: Put even or odd fields on first line of output video. The correct setting depends on your video clip. If static video jumps up and down slightly when you step through it, change this setting.

  • Interlace threshold: Controls the detection of interlace patterns. Lower values deinterlaces more.

  • Edge detect: It's difficult to distinguish between interlace lines and real edges (which should not be deinterlaced). This value controls this decision. Higher value leaves more edges intact.

  • Static threshold: The filter tries to detect static areas to avoid deinterlacing fine details which could result in flickering. This value controls how much a pixel can variate and still be called static. Use as low value as possible to avoid leaving interlace patterns. Values above 50 (or so) are not recommended. Good quality video can use lower values. If you don't have any text or logos that may flicker I suggest using very low values. 0 makes it work like version 1.0.

  • Static averaging: Controls how long history to look at when determining if areas are static or not. Low values (= short history) find static fast (but maybe incorrectly, leaving interlace patterns). High values means static details may flicker for a longer time before "converging". Also, it can be slower to react when areas go from static to non-static. Valid range is 0-100. A good rule is to set &ltstatic averaging> = 2 * &ltstatic threshold>, or higher (but don't get too close to 100).

  • Log to file: The frames that have an interlaced area exceeding the given number of percent can be logged to a file which will be placed in the current directory. It's called DeinterlaceSmooth.log and contains frame numbers and the interlaced area (in %) for each frame.

Version history:
Version 1.1: Often, fine detailed static areas such as text would get deinterlaced in version 1.0 resulting in flickering. It now tries to detect static areas by looking at several old frames/fields and leave those areas alone. Thanks to Janik for ideas and testing. (He has a great deinterlacing page at www.100fps.com btw).

Download the smooth deinterlacer
(Source code is available here)

 


General convolution 3D

This filter is a general 5x5 convolution filter with an extra dimension - time. It applies one matrix to the current frame, another matrix to the previous and yet another one to the frame prior to that. This filter was suggested by Neil Lee.

Settings

  • Use output instead of input for previous frame: Determines which previous frame to use. If checked, it uses the previous frame as it looked AFTER this filter processed it. Otherwise, it uses the unfiltered previous frame.

Version history:
Version 1.1: Went from matrix size 3x3 to 5x5 and from two to three matrixes (suggested by Roger Kamben). It's also faster when you don't use all the matrixes or matrixes smaller than 5x5.

Download General convolution 3D
(Source code is available here)

 


Deshaker

Deshaker is a video stabilizer. It has its own page here.

Video Size Calculator

Let's say you have captured a movie with black letterbox borders that you don't want in your final video and you want to view it in correct aspect ratio on a monitor. How much should you crop and resize the frames to get correct pixel ratio and at the same time force the width and height to be a multiple of, say, 16 (which is required for most codecs).
I soon got tired of doing these calculations time after time, so I made this little video size calculator. It can convert between standard PAL, standard NTSC, anamorphic PAL, anamorphic NTSC, SVCD and monitor. Well, it doesn't actually convert, just gives you some numbers to put into VirtualDub or other video tools. Try it!
Many people don't seem to be aware of the fact that you always need to resize your captured video to get correct aspect ratio on a monitor. At least if your capture resolution isn't 4:3. Another option is to use a media player that can alter the aspect ratio at playback time. This is actually an even better solution, because then you won't have to resize the original video at all, and resizing is no good for video quality no matter how good the resizing algorithm is.

Version history:
Version 1.02: The pixel aspect ratios used in the the calculations were changed to those described here. The changes are very subtle, though.

Download Video Size Calculator

If you feel like giving me a little something for my efforts...

2014 Gunnar Thalin

www.guthspot.se